Controls for heat pumps



April 14, 1964 w. K. KYLE CONTROLS FOR HEAT PUMPS Filed Nov. 20, 1962450 E4 KOOPSO E moooz Izweniow: W 11:11:91? by W \7.

u'zlformey 3,128,607 CONTROLS FOR HEAT PUMPS William K. Kyle, Staunton,Va., assignor to Westinghouse Electric Corporation, East Pittsburgh,Pa., a corpora tion of Pennsylvania Filed Nov. 20, 1962, Ser. No.238,900 3 Claims. (Cl. 62-158) This invention relates to heat pumps thatare used for heating or cooling indoor air.

Heat pumps that are used for cooling or heating indoor air usuallyconsist of motor driven refrigerant compressors that are connectedthrough solenoid adjusted, refrigerant reversal valves to indoor coilsand to outdoor coils. When indoorv air cooling is required, the reversalvalve is adjusted to route refrigerant from a compressor through anoutdoor coil acting as a condenser coil, and then through refrigerantexpansion means into an indoor coil acting as an evaporator coil. Whenindoor air heating is required, the reversal valve is adjusted to routerefrigerant from the compressor through the indoor coil acting as acondenser coil, and then through expansion means into the outdoor coilacting as an evaporator coil.

Some such heat pumps have heat thermostats which act to energizesolenoids to adjust the refrigerant reversal valves to indoor airheating positions, and to cycle the compressors when indoor air heat isrequired, and which act to deenergize the solenoids for causing thereversal valves to move to indoor air cooling positions when no indoorair heating is required. The cool thermostats of such heat pumps cyclethe compressors only. In such a heat pump, when the heat thermostat issatisfied after a period of indoor air heating, it stops thecompressormotor and deenergizes the solenoid of the reversal valve to cause thevalve to switch to its indoor air cooling position. At such a time, thehigh pressure gas in the indoor coil is released through the compressorinto the outdoor coil, producing objectionable noise.

This invention prevents or greatly reduces such a noise by maintainingthe reversal valve in its indoor air heating position for a period oftime after the heat thermostat has acted to reverse it, sufiicient forthe high pressure within the indoor coil to be reduced, thus preventingthe rush of high pressure gas through the compressor into the outdoorcoil. Time delay relay means is used to deenergize the solenoid a periodof time after the heat thermostat has opened its switch, suflicient forthe pressures in the indoor and outdoor coils to equalize. Such a timedelay means must be of the instantaneous make type so that indoor heatcan be produced quickly when required, and of the slow break type fordelaying the adjustment of the reversal valve from its air heatingposition. The available relays having these characteristics arerelatively expensive-in the $30.00 range. A feature of this invention isthat an instantaneous make-break relay costing about $1.25 is used witha slow make-slow break relay costing about $2.25 to provide theinstantaneous make and slow break action required.

An object of this invention is to reduce the noise resulting from theadjustment of a reversal valve of a heat pump from heating to coolingposition.

Another object of this invention is to provide inexpensive instantaneousmake and slow break relay means for quickly energizing the solenoid of areversal valve of a heat pump to adjust the valve to its heatingposition, and for delaying the deenergization of the solenoid.

This invention will now be described with reference to the annexeddrawing which is a diagrammatic view of a heating pump system embodyingthis invention.

A refrigerant compressor C driven by an electric motor M is connectedthrough tube to a conventional 3,128,607. Patented Apr. 14., 1964refrigerant reversal valve RV adjustable by solenoid S from indoor aircooling to indoor air heating positions and vice versa. to indoor aircoil 12, by a tube 13 to outdoor coil 14, and by a tube 15 toanaccumulator 16 which is connected bya tube 17 to the suction side ofthe compressor.

The coils 12 and 14 are connected by a capillary tube The tube 18contains a check-valve type restrictor 20 for decreasingthe refrigerantflowing to the indoor coil 12 when it is 18, serving as a two-wayexpansion means.

acting as acondenser coil, as disclosedin the G. L. Biehn Patent No.2,785,540. The solid line arrows show the direction of flow ofrefrigerant during indoor air heating, and the dashed line arrows showthe direction of flow of refrigerant during indoor air cooling.

Thesolenoid S is connected bya wire 22 to electric supply line L2, andby wire 23 to two-way switch arm 24 of thermal time delay relay TDR.Contact 25 of the relay TDR is connected to switch 26 of instantaneousrelay IR, which is connected to electric supply line L1.

Heater resistor 28 of the relay TDR is connected across coil 29 of therelay IR. The other contact 30 of the relay TDR is connected by wire31to the supply line' L1. The coil 29 is connected by wire 32 to the lineL2, and is connected to contact 33 of heat thermostat HT.

The switch arm 34 of the thermostat HT is connected to The compressormotor M is connected to the supply line-L2 and through switch 36 ofmotor starter relay MSR to the line L1. The relay MSR has an energizingcoil 37 connected to the line L2 and to contact the line L1.

43 of the thermostat HT- and-contact 40 of coolthermostat CT. Contactarm 41 of the thermostat CT is connected to the. supply line L1.

against the contact 25.

Operation In operation, assume that the cool thermostat is satisfiedafter the heat pump has been operating to cool indoor air, and itsswitch arm 41 leaves the contact 40. This deenergizes the motor starterrelay MSR which opens its switch 36, deenergizing the compressor motorM. Assume that thereafter the heat thermostat HT calls for heat. Itsswitch arm 34 moves against the contacts 33 and 43. The motor starterrelay MSR is energized through the connection of its coil directly tothe line L2, and through the contact 43 and switch arm 34 to the lineL1, and closes its switch 36, starting the compressor motor M. The relayIR is energized through the connection of its coil 29 to the line L2,and through the contact 33 and switch arm 34 to the line L1, and closesits switch 26 connecting the solenoid S to the supply line L1 throughthe wire 23, the switch arm 24, the contact 25 and the closed switch 26.The solenoid is already connected to the other line L2 and is energizedand adjusts the reversal valve RV to its air heating position. At thesame time, the heater resistor 28 is energized and after becoming fullyheated, deflects the switch arm 24 so quickly from the contact 25 toagainst the contact 30 which is connected by the wire 31 to the line L1that the solenoid remains in air heating position and maintains thereversal valve RV in air heating position.

When the reversal valve is so switched to air heating position, thecompressor motor M has previously been stopped by the cool thermostat sothat the pressures between the high and low sides of the compressor havehad time to equalize so that there is no noise produced by the switchingin this direction.

When the heat thermostat HT is satisfied, its switch arm 34 leaves thecontacts 33 and 43. The switch arm 34 leaving the contact 43 deenergizesthe motor starter The valve RV is connected by a tube 11 When theheaterresistor- 28 of the relay TDR is cold, the switch arm 24 restsrelay MSR and stops the compressor motor M. The switch arm 34 leavingthe contact 33 deenergizes the relay IR which opens the switch 26disconnecting the contact 25 from the supply line L1. At the same time,the heater resistor 28 of the time delay relay TDR is deenergized. Theresistor 28 cools, but a period of time is required for it to havedissipated sufiicient heat to permit the switch arm to leave the contact30 and deenergize the solenoid S. The reversal valve RV thus remains inits indoor air heating position after the heat thermostat is satisfieldfor a period of time sufficient for the pressure between the high andlow sides of the compressor to have equalized so that there is no noisecaused by the rush of high pressure gas into the low side of thecompressor when the reversal valve switches to its heating position.

What is claimed is:

l. A heat pump comprising an indoor air coil, an outdoor air coil, arefrigerant compressor, an electric motor for driving said compressor,means including a refrigerant reversal valve for connecting said coilsto said compressor, a solenoid for adjusting said valve to routerefrigerant from said compressor to said outdoor coil and then to saidindoor coil or to route refrigerant from said compressor to said indoorcoil and then to said outdoor coil, a first thermostat, electric supplyconnections, means including said thermostat for connecting said motorto said connections, relay means, a normally open quick make switchwhich closes when said relay means is energized, a normally closed slowbreak switch which opens when said relay means is energized, a secondthermostat, means including said second thermostat for connecting saidmotor and said relay means to said connections, and means including saidswitches in series for connecting said solenoid to said connections.

' 2. A heat pump comprising an indoor air coil, an outdoor air coil, arefrigerant compressor, an electric motor for driving said compressor,means including a refrigerant reversal valve for connecting said coilsto said compressor,

a solenoid for adjusting said valve, said solenoid when deenergizedadjusting said valve to route refrigerant from said compressor to saidoutdoor coil and then to said indoor coil and when energized adjustingsaid valve to route refrigerant from said compressor to said indoor coiland then to said outdoor coil, a first thermostat for controlling saidheat pump during air cooling operation, electric supply connections,means including said thermostat for connecting said motor to saidconnections, relay means, having a normally open quick make switch whichcloses when said relay means is energized, a normally closed slow breakswitch which opens when said relay means is energized, a secondthermostat for controlling said heat pump during air heating operation,means including said second thermostat for connecting said motor andsaid relay means to said connections, and means including said switchesin series for connecting said solenoid to said connections.

, 3. A heat pump comprising an indoor air coil, an outdoor air coil, arefrigerant compressor, an electric motor for driving said compressor,means including a refrigerant reversal valve for connecting said coilsto said compressor, a solenoid for adjusting said valve to routerefrigerant from said compressor to said outdoor coil and then to saidindoor coil or to route refrigerant from said compressor to said indoorcoil and then to said outdoor coil, a first thermostat, electric supplyconnections, means including said thermostat for connecting said motorto said connections, a first relay having a quick make switch, a secondrelay having a slow break switch, a second thermostat, means includingsaid second thermostat for connecting said motor and said relays to saidconnections, and means including said switches for connecting saidsolenoid to said connections.

References Cited in the file of this patent UNITED STATES PATENTS2,713,250 Blatchford July 19, 1955

1. A HEAT PUMP COMPRISING AN INDOOR AIR COIL, AN OUTDOOR AIR COIL, AREFRIGERANT COMPRESSOR, AN ELECTRIC MOTOR FOR DRIVING SAID COMPRESSOR,MEANS INCLUDING A REFRIGERANT REVERSAL VALVE FOR CONNECTING SAID COILSTO SAID COMPRESSOR, A SOLENOID FOR ADJUSTING SAID VALVE TO ROUTEREFRIGERANT FROM SAID COMPRESSOR TO SAID OUTDOOR COIL AND THEN TO SAIDINDOOR COIL OR TO ROUTE REFRIGERANT FROM SAID COMPRESSOR TO SAID INDOORCOIL AND THEN TO SAID OUTDOOR COIL, A FIRST THERMOSTAT, ELECTRIC SUPPLYCONNECTIONS, MEANS INCLUDING SAID THERMOSTAT FOR CONNECTING SAID MOTORTO SAID CONNECTIONS, RELAY MEANS, A NORMALLY OPEN QUICK MAKE SWITCHWHICH CLOSES WHEN SAID RELAY